Issue: December 2020
Perspective from Elizabeth N. Pearce, MD, MSc
Disclosures: The authors report no relevant financial disclosures.
October 22, 2020
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Metabolic management restores thyroid function in adults with type 2 diabetes

Issue: December 2020
Perspective from Elizabeth N. Pearce, MD, MSc
Disclosures: The authors report no relevant financial disclosures.
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Adults in China with type 2 diabetes had improved glucose control and a restoration of thyroid function after participating in metabolic management, according to a study published in the Journal of Diabetes.

“Patients with type 2 diabetes had significantly lower levels of free triiodothyronine

Metabolic management

and free thyroxine within normal reference range than patients with normal glucose tolerance and prediabetes,” Yufan Wang, MD, PhD, professor in the department of endocrinology and metabolism at Shanghai General Hospital, Shanghai Jiao Tong University School of Medicine, and colleagues wrote. “Free T3 and ree T4 levels were negatively associated with HbA1c level and positively associated with estimated glucose disposal rate. After National Metabolic Management Center standardized management, the metabolic status in the diabetes uncontrolled group dramatically improved ... Thyroid hormone levels were restored to normal after metabolic status improved in type 2 diabetes patients.”

Researchers recruited 2,000 participants who were undergoing treatment at the National Metabolic Management Center of Shanghai General Hospital and had a community physical examination from September 2017 to August 2019. Participants were split into four groups based on blood glucose level at baseline: individuals without diabetes (n = 132), with prediabetes (n = 147), well-controlled diabetes for individuals with type 2 diabetes and an HbA1c of 7% or less (n = 505) and uncontrolled diabetes for with type 2 diabetes and an HbA1c of more than 7% (n = 1,216). Participants in the diabetes groups received standardized management care at the National Metabolic Management Center, where they could receive services including examinations, evaluation, prescriptions and health education.

At baseline, the group had the highest mean levels of free T3 (4.76 pmol/L) and free T4 (17.74 pmol/L), followed by the prediabetes group (mean free T3 4.72 pmol/L; mean free T4 16.74 pmol/L). The controlled diabetes cohort had a lower mean free T3 of 4.59 pmol/L and a lower mean free T4 of 15.65 pmol/L than the group without diabetes and the prediabetes cohort. The uncontrolled diabetes group also had lower mean free T3 (4.46 pmol/L) and free T4 levels (15.69 pmol/L). There was no significant difference in thyroid-stimulating hormone between the four groups.

After adjusting for age, sex, use of drugs, use of lipid-lowering drugs, diabetes duration, BMI and waist-hip ratio, free T3 was negatively correlated with fasting plasma glucose and positively correlated with estimate glucose disposal rate in the two diabetes groups. No relationship was found between and blood glucose levels.

Researchers followed up with 254 individuals in the uncontrolled diabetes group 1 year after baseline (mean age, 49.4 years). The cohort showed improvement in most metabolic parameters at 1 year, with mean FPG decreasing from 7.8 mmol/L at baseline to 6.5 mmol/L at follow-up, postprandial plasma glucose decreasing from 14.3 mmol/L at baseline to 10.9 mmol/L at follow-up, and mean HbA1c dropping from 8.7% at baseline to 6.7% at follow-up. The mean estimated glucose disposal rate increased from 7.59 mg/kg/min to 8.86 mg/kg/min (P < .001 for all).

Concentrations of free T3 increased in the follow-up group from 4.51 pmol/L at baseline to 4.68 pmol/L after year (P < .05). No significant difference was found in T4 levels. Reverse T3 decreased from 1.03 nmol/L at baseline to 0.92 nmol/L at follow-up and dropped from 2.18 mIU/L to .7 mIU/L (P < .001).

Researchers also followed up with 82 adults in the well-controlled diabetes cohort. The group had improved , BMI and waist-hip ratios at follow-up, whe HbA1c remained unchanged. decreased from 2.42 mIU/L at baseline to mIU/L at follow-up (P < .05) and reverse T3 levels decreased from 1.04 nmol/L to 0.94 nmol/L.

“Our study suggested that low free thyroid hormone levels in normal range were significantly associated with high glucose level and severe insulin resistance,” researchers wrote. “For poorly controlled type 2 diabetes, Metabolic Management Center -year standardized management not only improved blood glucose levels, insulin resistance and other metabolic indicators, but restored thyroid function as well.”